1. Field of the Invention
The present invention relates to a disk drive capable of effecting the loading and ejection of a magnetic recording medium smoothly and capable of preventing the recording medium from being ejected even in the event an eject button should be pushed by mistake during operation.
2. Description of the Related Art
A magnetic recording medium, typical of which is a floppy disk, is loaded into a disk drive in the form of a disk cartridge with a thin film-like magnetic disk received in a shell, then the magnetic disk is rotated within the disk drive, and writing and reading of information are performed by means of a magnetic head which is inserted into the shell through a window with shutter formed in the shell. In the disk drive, such a mechanism as schematically shown in FIG. 8 has heretofore been used for the loading and ejection of the magnetic recording medium.
In the conventional disk drive, as shown in FIG. 8, a lower plate 102 and an upper plate 103 are superimposed in this order on a base plate 101. A rotor (not shown) is mounted at a center of the base plate 101 and it comes into engagement with a center hub attached to a magnetic disk of a magnetic recording medium F to rotate the magnetic disk in a certain direction. The lower plate 102 is mounted on the base plate 101 so as to be movable in the longitudinal direction and its central portion is gouged out so that its movement does not obstruct the rotation of the rotor. An eject button 105 is attached to a front edge portion of the lower plate 102. The upper plate 103 is mounted on the lower plate 102 so that it can be moved upward and downward in two stages interlockedly with backward and forward movements of the lower plate by means of a mechanism (not shown). Between the upper plate 103 and the lower plate 102 is formed a gap and the magnetic recording medium F is inserted into the gap through a front inlet opening 104.
A longitudinally extending cutout portion 106 is formed at a center of a rear portion of the upper plate 103, and within this cutout portion a carriage 110 with a magnetic head carried thereon extends forward from a rear portion of the substrate. In the carriage 110, two head holders 112a and 112b, which are superimposed one on the other, extend forward from a carriage body 111, and magnetic heads are attached respectively to front ends of the head holders, the magnetic heads being opposed to each other with the magnetic recording medium therebetween. Of both head holders, the upper head holder 112a is pivotally movable through a hinge 113 and is urged downward by means of a spring (not shown) The upper head holder 112a has a pair of transversely extending arm portions 114. The arm portions 114 extend beyond the cutout portion 106 and are superimposed on the upper plate 103.
In the above prior art, the carriage 110 can be moved in the longitudinal direction along a guide rail 116 by means of a drive unit 115 which as a whole is constituted by a combination of a worm shaft 115a and a pulse motor 115b, the pulse motor 115b being controlled by a computer.
When the magnetic recording medium F is not inserted into the disk drive, the lower plate 102 assumes a rear position and the upper plate 103 is held at its upper-stage position by a lift lock mechanism (not shown), whereby the gap between the upper and lower plates is widened, permitting the magnetic recording medium F to be inserted freely into the gap. At this time, the upper head holder 112a is raised together with the upper plate 103 by means of its arm portions 114, so that the upper head holder 112a is open upward and does not obstruct the insertion of the recording medium F.
An eject lock mechanism 120 is provided at a right-hand rear position in the figure of the base plate 101. Upon insertion of the magnetic recording medium F and abutment of its tip against a shutter opening/closing lever 122 of the eject lock mechanism 120, the lever 122 slides on an edge portion of the recording medium F and opens a shutter S, allowing the magnetic disk to be exposed. At the same time, a lift lock lever 121, which is interlocked with the shutter opening/closing lever 122, operates to move the lower plate 102 forward so that the upper plate 103, which is interlocked with the lower plate, moves down to its lower stage. Consequently, the recording medium F is held between the lower plate 102 and the upper plate 103 and is fixed thereby. The upper head holder 112a also moves down, so that the upper and lower magnetic heads come into a state of pseudo-contact with the magnetic disk, thus assuming a stand-by state for write and read (work).
When the eject button 105 is pushed upon completion of the work, the lower plate 102 moves backward and pushes the lift lock lever 121 and is thereby locked at a rear position. As a result, the upper plate 103 moves to its upper stage together with the upper head holder 112a. At the same time, the shutter opening/closing lever 122 interlocked with the lift lock lever 121 closes the shutter S and the magnetic recording medium F is caused to spring out forward by virtue of a spring (not shown).
The above conventional loading and ejection mechanism involves a problem that, if the eject button 105 should be pushed by mistake during work, the magnetic recording medium F is ejected immediately and the work is interrupted. Moreover, if the supply of electricity is stopped due to, for example, a power failure during work, the upper and lower magnetic heads are left in pseudo-contact with the magnetic disk, so that when the supply of electricity is restarted, the magnetic heads may come into abnormal contact with the magnetic disk and damage the disk. Further, since the vertical movements of the upper plate 103 and the upper head holder 112a are each performed with a repulsive force of a spring, a large shock is induced. Particularly, there has been a problem that when the upper head holder 112a moves down, the magnetic heads strike against and damage the magnetic disk due to a reaction.
Additionally, with the recent increase in capacity of the magnetic recording medium and fine structure of the magnetic head, high accuracy and speed have also come to be required for positioning the magnetic head. Instead of the conventional drive unit 115 constituted by a combination of the worm shaft 115a and the pulse motor 115b, which is shown in FIG. 8, a so-called voice coil motor of linear drive has come to be used, which is provided with a voice coil on the carriage side and a magnet and a yoke on the substrate side and in which the positions of the magnetic heads can be set in the longitudinal direction at high speed and precisely by energizing the voice coil. In this type of a disk drive, the voice coil is not energized and the carriage may move back and forth freely. However, and upon tilting of the disk drive or exertion of an external force, the carriage may crash against a guide rail end, resulting in deformation thereof or damage of the magnetic heads.